Magnetic resonance scanner with electromagnetic position and orientation tracking device

• US 20030184297A1
• Filed: 03/17/2003
• Published: 10/02/2003
• Est. Priority Date: 12/23/1998
• Status: Active Grant

• Current Assignee: Peter D. Jakab
• Original Assignee: Peter D. Jakab
• Inventors: Jakab, Peter D.
• Granted Patent: US 6,879,160 B2
• Time in Patent Office: Days
• US Class Current: 324/318
• CPC Class Codes: G01R 33/285 Invasive instruments, e.g. catheters or biopsy needles, specially adapted for tracking, guiding or visualization by NMR

Abstract

A system for combining electromagnetic position and orientation tracking with magnetic resonance scanner is provided. One embodiment includes a magnetic resonance scanner defining a reference coordinate system for scanning a target. Coupled to the magnetic resonance scanner is a magnetic field source which produces a magnetic field. The magnetic field is sensed by a magnetic field sensor which produces a signal proportional to the magnetic field. The magnetic field sensor has a location relative to the reference coordinate system. The location of the magnetic field sensor relative to the reference coordinate system of the magnetic resonance scanner is determined by a location tracking device using at least a line segment model of the magnetic field source and the signal from the magnetic field sensor.

Claims

1. A magnetic resonance device, the device comprising:

a repositionable magnetic field assembly, generating a static magnetic field having a homogeneous region at a known location relative to the magnetic field assembly, creating a precession of a nuclei of a target sample of a subject within the homogeneous region, generating a spatially distinct magnetic field for position and orientation tracking of the target sample relative to the homogeneous region and obtaining a magnetic resonance signal of the target sample within the homogeneous region for each position of the repositionable magnetic field assembly; and

a processor for computing a magnetic resonance output wherein a sensor signal representative of the spatially distinct magnetic field is associated with a magnetic resonance signal thereby providing spatial information.

2. The device according to claim 1, further comprising:

a sensor attachable to the subject for sensing the spatially distinct magnetic field and providing the sensor signal dependent upon the position and orientation of the target sample to the processor.

3. The magnetic resonance device according to claim 1 wherein the processor calculates the position and orientation of the target sample relative to the homogeneous region.

4. The magnetic resonance device according to claim 1 wherein the magnetic field assembly produces a radio frequency magnetic field for creating a precession of the nuclei of the target sample residing in the homogeneous region.

5. The magnetic resonance device according to claim 1 wherein when the repositionable magnetic field assembly is repositioned relative to the subject, the processor determines the position and orientation of the target sample relative to the homogeneous region and combines the magnetic resonance signals from different position and orientations to form a scan.

6. The magnetic resonance device according to claim 1, creating a scan of the target sample without using gradient magnetic field encoding.

7. The magnetic resonance device according to claim 1, wherein the processor executes a pulse sequence to generate the radio frequency magnetic field and to collect each resulting magnetic resonance signal.

8. The magnetic resonance device according to claim 1, wherein the processor generates a signal to control the magnetic field assembly, wherein the signal causes the magnetic field assembly to generate the radio frequency magnetic field.

9. The magnetic resonance device according to claim 1, wherein the processor collects each magnetic resonance signal received by the magnetic field assembly.

10. The magnetic resonance device according to claim 1, wherein the processor generates signals to control the magnetic field assembly, wherein the signals cause the magnetic field assembly to generate the spatially distinct magnetic field.

11. The magnetic resonance device according to claim 1, further comprising:

a sensor for attachment to the subject, the sensor sensing the spatially distinct magnetic field.

12. The magnetic resonance device according to claim 11, wherein the processor receives the sensor signal from the sensor representative of the spatially distinct magnetic field.

13. The magnetic resonance device according to claim 11, wherein the processor calculates the position and orientation of the target sample relative to the homogeneous region from the sensor signal.

14. The magnetic resonance device according to claim 1, wherein the processor detects a change in the position of the target sample relative to the homogeneous region.

15. The magnetic resonance device according to claim 1, wherein the processor causes a new magnetic resonance signal to be obtained if the position of the target sample relative to the homogeneous region is changed.

16. The magnetic resonance device according to claim 1, wherein the processor causes a new magnetic resonance signal to be obtained after a predetermined period of time.

17. The magnetic resonance device according to claim 1, wherein the processor computes a display signal from the magnetic resonance signals and their corresponding spatial information.

18. The magnetic resonance device according to claim 1, wherein the processor outputs the display signal capable of being displayed on a display device.

19. The magnetic resonance device according to claim 1, further comprising a display device for at least displaying an image of at least a portion of the subject.

20. The magnetic resonance device according to claim 1, wherein the magnetic field assembly is provided in a hand-held structure.

21. The magnetic resonance device according to claim 1, wherein at least the magnetic field assembly is positioned on a support structure which is movable.

22. The magnetic resonance device according to claim 1, wherein the processor initializes the position and orientation of the target sample relative to the homogeneous region.

23. The magnetic resonance device according to claim 1, wherein the processor calculates the position and orientation of the homogeneous region relative to the magnetic field assembly.

24. The magnetic resonance device according to claim 1, wherein the processor calculates the position and orientation of the sensor relative to the magnetic field assembly.

25. The magnetic resonance device according to claim 1, wherein the processor calculates the position and orientation of the target sample relative to the sensor.

26. The magnetic resonance device according to claim 1, wherein the processor recalculates the position and orientation of the target sample relative to the homogeneous region.

27. The magnetic resonance device according to claim 1 further comprising:

a second sensor attached to a moveable object to track the position and orientation of the moveable object.

28. The magnetic resonance device according to claim 27, wherein the processor initializes the position and orientation of the moveable object relative to the second sensor.

29. The magnetic resonance device according to claim 27, wherein the processor calculates the position and orientation of the second sensor relative to the magnetic field assembly.

30. The magnetic resonance device according to claim 27, wherein the processor calculates the position and orientation of the moveable object relative to the magnetic field assembly.

31. The magnetic resonance device according to claim 27, wherein the processor computes a display signal from the magnetic resonance signals and their corresponding spatial information and the position and orientation of the moveable object.

32. A method for magnetic resonance imaging a target sample of a subject, the method comprising:

generating a static magnetic field having a homogeneous region with a magnetic field generating assembly;

positioning the magnetic field generating assembly to a first position so that the homogeneous region is within at least a portion of the target sample of the subject;

generating a first magnetic field having spatially distinct properties;

sensing the first spatially distinct magnetic field;

calculating the first location of the subject relative to the homogeneous region from the sensed first spatially distinct magnetic field;

generating a first radio frequency magnetic field for creating a precession of a nuclei in the target sample in the homogeneous region;

receiving a first magnetic resonance signal corresponding to the first location at the first position;

repositioning the static magnetic field generating assembly to a second position wherein at least a portion of the target sample of the subject is within the homogeneous region;

generating a second magnetic field having spatially distinct properties;

sensing the second spatially distinct magnetic field;

calculating the second location of the subject relative to the homogeneous region from the sensed second spatially distinct magnetic field;

generating a second radio frequency magnetic field for creating a precession of a nuclei in the target sample in the homogeneous region;

receiving a second magnetic resonance signal corresponding to the second location-at the second position; and

combining the magnetic resonance signals to form an image of the target sample of the subject based upon and the locations at the first position and the second position.

33. A method for magnetic resonance imaging according to claim 32, further comprising:

generating a first and second set of magnetic field gradients to spatially encode the first and second magnetic resonance signals.

34. A method for magnetic resonance imaging according to claim 33, further comprising:

creating a spatially decoded first and second magnetic resonance signals.

35. A method for magnetic resonance imaging according to claim 34, further comprising:

combining the spatially decoded magnetic resonance signals to form an image of the target sample of the subject based upon and the locations at the first position and the second position.

36. A method for magnetic resonance imaging according to claim 32, further comprising:

calculating a position and orientation of a magnetic field sensor relative to a position and orientation of the magnetic field assembly based on a model of magnetic field generation of the magnetic field assembly, a measured electric current value of the magnetic field assembly, a model of magnetic field sensing of the magnetic field sensor and a measured signal of the magnetic field sensor.

37. A method for magnetic resonance imaging according to claim 36, further comprising:

calculating the position and orientation of the magnetic field sensor relative to the position and orientation of the homogeneous region of the static magnetic field, based on a calibrated value of the position and orientation of the homogeneous region relative to the static magnetic field assembly.

38. A method for magnetic resonance imaging according to claim 36, further comprising:

obtaining an initial value of the position and orientation of the target sample relative to the magnetic field sensor.

39. A method for magnetic resonance imaging according to claim 36, further comprising:

calculating position of the target sample relative to the position and orientation of the homogeneous region, based on the initial value of the position and orientation of the target sample relative to the magnetic field sensor and the position and orientation of the sensor relative to the homogeneous region of the static magnetic field.

40. A method for magnetic resonance imaging according to claim 36, further comprising:

mapping the magnetic resonance signal onto an image space, based on the position and orientation of the target sample relative to the homogeneous region of the static magnetic field.

41. A method for magnetic resonance imaging according to claim 36, further comprising:

mapping the spatially decoded magnetic resonance signal onto an image space, based on the position and orientation of the target sample relative to the homogeneous region of the static magnetic field and the decoded spatial information of the spatially decoded magnetic resonance signal.

42. A method for magnetic resonance imaging according to claim 32, further comprising:

calculating a position and orientation of a second magnetic field sensor relative to the homogeneous region of the static magnetic field assembly.

43. A method for magnetic resonance imaging according to claim 42, further comprising:

mapping the position and orientation of a moveable object onto the image space, based on the position and orientation of the second magnetic field sensor, a calibrated value of the position and orientation of the moveable object relative to the second magnetic field sensor.

44. A method for magnetic resonance imaging according to claim 42, further comprising:

generating a display output from the values in the image space.